Chad Reed's 2004 YZ250

When two-strokes ruled the Earth

Chad Reed's 2004 YZ250

It’s amazing what a couple of years can do.  

Today, four-strokes dominate the premier class of the AMA Amp’d Mobile Supercross Series, but in 2004, faster-revving two-strokes still dominated on the series’ tight, technical indoor tracks.  

The fastest of them all that year? Chad Reed’s Yamaha YZ250.  

Reed used this machine to win 10 of 16 races en route to his first and only AMA National Championship, over Honda’s Kevin Windham.  

For Reed, the trick Yamaha was the right tool at the right time. Based on the company’s production machine, this YZ was assembled by team mechanic Darrin Sorenson with parts from Yamaha Japan, Yamaha Motors USA and aftermarket companies.  

In the motor, a programmable ignition and a modified reed block, cylinder and cylinder head produce the explosive acceleration that allowed Reed to clear 80-foot triples with only 30 feet of run-up. And to make the landing as predictable as the takeoff, the bike features a bell-bottom Kayaba front fork—a prototype modified specifically for Reed’s riding style.  

Other top-shelf bits include a billet aluminum triple-clamp, a custom shock linkage, magnesium hubs, titanium fasteners and a transmission with custom ratios. Titanium footpegs, a carbon-fiber skidplate and a special clutch lever that Reed could adjust while in the heat of battle round out the package.  

To complete modifications to the stock YZ, the team relied on a number of aftermarket companies. The brakes are by Nissin, the pipe and silencer are sourced from Pro Circuit and the knobbies are made by Bridgestone.  


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two-stroke single




Bore & Stroke
66.4mm x 72mm


Mikuni with throttle
position sensor
and power jet


Front/rear: 14/55


219.5 lbs.


Motors Corp.


Click to enlarge